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Year : 2019  |  Volume : 10  |  Issue : 4  |  Page : 173-177

In vitro study of the periapical sealing ability of three root canal sealing cement

1 Department of Stomatology, University of Seville, School of Dentistry, Seville, Spain
2 Department of Health Care, Metropolitan Autonomous University-Xochimilco, Mexico City, Mexico
3 Interdisciplinary Research Center Egas Moriz, University Institute Egas Moniz Egas Moniz, Instituto Universitário Egas Moniz, Quinta Da Granja, Monte De Caparica, Caparica, Portugal

Date of Submission17-Oct-2019
Date of Acceptance20-Nov-2019
Date of Web Publication22-Jan-2020

Correspondence Address:
Dr. Ignacio Barbero-Navarro
Facultad De Odontología Universidad De Sevilla, Calle Avicena S/n Cp 41009, Sevilla
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DOI: 10.4103/srmjrds.srmjrds_72_19

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Objective: The objective of this study was to determine the sealing ability of different root canal cement: resin AH Plus®, calcium hydroxide Sealapex®, and eugenol zinc oxide Pulp Canal Sealer® by measuring the apical penetration of a dye. Methods: One hundred straight single-canal teeth were biomechanically prepared to 0.5 mm of the apical foramen. The teeth were divided into four groups, three experimental groups, with thirty teeth in each group, and a control group, with ten teeth. The following sealants were selected: AH Plus®, Sealapex®, and Pulp Canal Sealer®. The root canal was not sealed in the control group. Lateral condensation was performed on the experimental groups using gutta-percha. The teeth were immersed in Indian ink to determine leakage. Results: In the experimental groups, ink penetration was observed in about 50% of the teeth. The lowest mean penetration was observed in the AH Plus® group (30.9 (±42.9)), and the highest was observed in Pulp Canal Sealer® (94.35 [±79.9]), (P < 0.001). Sealapex® (42.7 [±56.3]) had lower ink penetration than Pulp Canal Sealer® (P < 0.005). No statistically significant difference was observed in dye penetration between AH Plus® and Sealapex® (P = 0.2931). Conclusion: Low dye periapical penetration was observed using AH Plus and the calcium hydroxide cement (Sealapex®), while higher penetration was observed in Pulp Canal Sealer®.

Keywords: Lateral condensation, periapical leakage, root filling, sealers, sealing cement

How to cite this article:
Barbero-Navarro I, Irigoyen-Camacho ME, Castano-Seiquer A, Zepeda-Zepeda MA, Martins F, Mauricio P. In vitro study of the periapical sealing ability of three root canal sealing cement. SRM J Res Dent Sci 2019;10:173-7

How to cite this URL:
Barbero-Navarro I, Irigoyen-Camacho ME, Castano-Seiquer A, Zepeda-Zepeda MA, Martins F, Mauricio P. In vitro study of the periapical sealing ability of three root canal sealing cement. SRM J Res Dent Sci [serial online] 2019 [cited 2020 Sep 29];10:173-7. Available from:

  Introduction Top

The success of endodontic treatment relies on the effective preparation, disinfection, and filling of the root canal system. In this context, “filling” implies complete obstruction of the canal system and its anatomical irregularities using an inert, dimensionally stable, and biologically compatible material (usually gutta-percha), combined with a suitable sealer cement.[1] A large percentage of endodontic failures are caused by incomplete canal filling. The perfect corono-apical sealing is determined by the use of a maximal amount of central core filling material (gutta-percha), with a minimum amount of sealer between the central inert core and the dentinal walls.[2] Endodontic sealer cement should be biocompatible and cause minimal irritation as they come into contact with the live tissues of the periodontal space through the apex. Furthermore, endodontic sealer cement should have good adhesion with the dentin in the root canal, and they should also make a hermetic seal. The sealer should not shrink upon setting nor discolor tooth structure. They should also be insoluble in tissue fluids and be radiopaque.[3]

The most commonly used core filling material is gutta-percha, which can be reasonably adjusted to the root canal walls. However, due to canal irregularities and the size of the dentinal tubules, a root canal sealer is also essential. A root canal sealer will not only assist in filling irregular spaces but also in enhancing the seal during compaction and penetration into small, normally inaccessible areas, i.e., the dentinal tubules.[4]

There are several types of root canal sealants. The most common types can be classified as resin base, calcium hydroxide, and zinc oxide eugenol. Several studies have compared the characteristics of these sealants, including their antimicrobial capacity.[5] Other studies have compared their physicomechanical characteristics.[6],[7] Despite the long-term use of AH Plus® (Dentsply DeTrey, Konstanz, Germany), Sealapex® (Kerr Co., Romulus, MI, USA), and Pulp Canal Sealer® (Kerr Co., Romulus, MI, USA), there are insufficient data comparing the sealing ability of these sealants. The aim of this study is to compare the apical leakage associated with a resin-based sealer, a calcium hydroxide sealer, and eugenol zinc oxide-based sealer using gutta-percha as a filling core in all cases.

  Methods Top

One hundred straight single-root teeth were removed for periodontal reasons and the remaining periodontal tissue was eliminated. The occupational safety and health administration recommendations and guidelines were followed.[8] The crowns were sectioned with a diamond disc below the cementoenamel junction, and the root was immersed in a 0.9% physiologic saline solution for 10 days. The canals were instrumented to a working length of 0.5 mm from the apical foramen. The crown-down technique was used with the ProTaper Universal (Dentsply Maillefer) rotary system, and the recommended sequence was followed (S1, S2, F1, F2, and F3). The root canals were made patent, and a glide path was made using 10 K Colorinox files (Dentsply Maillefer®) between each file size. Adequate irrigation with 5% NaClO was maintained during instrumentation of the canals.

The teeth were divided into three experimental groups, with thirty teeth in each group, and a control group, with ten teeth. The teeth in the experimental groups were then randomly assigned to one of the following: Group I: AH Plus®, Group II: Sealapex®, and Group III: Pulp Canal Sealer®. Rotary instruments with nickel–titanium files were used in the canals. In all cases, the filling cone was prepared with gutta-percha using a standardized technique. A lateral condensation technique was utilized with digital steel lateral condensers (Dentsply Maillefer®).

The samples from the experimental groups were kept for 5 days in an oven at 37°C and 100% relative humidity to complete the setting of the different sealers. All teeth were coated with two layers of nail varnish over nearly the entire root surface, with the exception of the last two apical millimeters. In the control group, the coronal access to the canal was left open allowing then ink to penetrate the root canal. The crown portion in the experimental groups was sealed with provisional cement Cavit® (3M ESPE, USA). In addition, this zone was covered with a layer of cyanoacrylate and two layers of nail varnish. All specimens were then placed in 1.5 ml Eppendorf tubes filled with Indian ink and centrifuged at 3000 rpm for 20 min in a Sigma 2K 15 centrifuge, to facilitate ink penetration through the apical foramen. The tubes were left to stand for 1 week. The samples were then extracted from the tubes and washed in distilled water. The nail varnish was eliminated using a solvent.

All of the teeth were subsequently rendered diaphanous through demineralization with 5% nitric acid, dehydrated in an alcohol series of increasing concentration (80% for 12 h, 90% for 2 h, and 100% for 2 h), and immersed in methyl salicylate until transparent.[7] Finally, dye penetration was evaluated using a surface stereomicroscope (Nikon® SMZ-10A, Tokyo, Japan) equipped with a calibrated lens to measure penetration in micrometers.

The results were expressed as mean (±standard deviation). Considering that the distribution of the dye penetration readings was not normally distributed, a nonparametric Kruskal–Wallis test was applied to analyze the difference between groups. The Steel-Dwass method was applied for all pairs. Each experimental group was dichotomized into teeth with dye penetration and teeth without dye penetration. A Chi-squared test was used to compare these groups. When required, the Fisher's exact test was applied. The level of significance was set at P< 0.05. The STATA V15, StataCorp LLC, College Station, Texas, USA statistical package was used for the data analysis.

  Results Top

The mean dye penetration found in the Pulp Canal Sealer® group was 94.3 (±79.9), the Sealapex® group was 42.7 (±56.3), and the AH Plus® group was 30.9 (±42.9). The difference in dye penetration among these sealers was statistically significant (P = 0.001). Comparisons between cement sealers showed a significant difference between Pulp Canal Sealer®, Sealapex®, and AH Plus®. Pulp Canal Sealer® had a higher dye penetration than Sealapex® (score mean difference: 12.6, 95% confidence interval [CI]: (8.3, 82.1), P = 0.0047) and AH Plus® ((score mean difference: 15.03, 95% CI (22.0, 96.0), P = 0.007). No statistically significant difference was observed between the AH Plus® group and Sealapex® (Score mean difference 4.57, 95% CI (0, 29.5), P = 0.2931). The positive control group showed a 100% dye penetration.

In the experimental groups, approximately two-thirds (65.5%) of the teeth studied showed an incomplete occlusion on the apical region. [Figure 1] depicts the percentage of teeth showing an incomplete apical occlusion. A higher percentage of complete apical occlusion (no dye penetration) was observed that the AH Plus® group (50%) than the Sealapex® (33.3%) (P = 0.0251) group. No statistically significant difference was observed in the percentage of teeth with dye penetration between Sealapex® and Pulp Canal Sealer® (P = 0.3257). [Figure 2]a depicts dye penetration in a tooth treated with AH Plus® and [Figure 2]b illustrates dye penetration in a tooth treated with Pulp Canal Sealer®. Higher dye penetration was observed in the tooth treated with Pulp Canal Sealer®.
Figure 1: Percentage of teeth with dye penetration using three sealants resin based (AH-Plus®), Sealapex® (calcium hydroxide), and zinc oxide eugenol (Pulp Canal Sealer®)

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Figure 2: (a) Scarce dye penetration in a tooth treated with AH Plus®. (b) Large amount of dye diffusing at the apex in a tooth treated with Pulp Canal Sealer®

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  Discussion Top

The findings of the present study showed that the Pulp Canal Sealer® (Zinc Oxide Eugenol (ZOE)-based sealer) group had a threefold higher ink penetration than the AH Plus® (resin-based sealer) group. The mean dye penetration was higher with Pulp Canal Sealer® than in the Sealapex® (calcium hydroxide based) sealer cement group. In addition, AH Plus® had a higher percentage of complete apical seal compared with Sealapex®. These observations suggest that the resin-based sealant, AH Plus, appears to be more effective in providing an adequate periapical seal than the other cement studied.

These findings agree with the conclusions of other ex vivo studies using different evaluation methods.[9],[10],[11] A study comparing apical microleakage of two sealing cement, Pulp Canal Sealer Extended Working Time (EWT) and AH Plus, found that the resin-based sealer cement had better results, lower voids formation in the apical region, and better filling scores in the lateral canals.[7] A comparison of Topseal (resin based), Roth 801 (ZOE based), and Apexit (calcium hydroxide based) in terms of their sealing ability in teeth with an iatrogenic disreputed apical construction found that Topseal was more effective than Roth 811 and Apexit.[9] Moreover, the B-epoxy resin sealers have shown strong adhesion to dentine and gutta-percha when compared with Sealapex and Zinc Oxide Eugenol.[10] Karapanou et al. found greater dye penetration of a ZOE cement (Roth 801®) in comparison to a resin sealant (AH26®).[11] This is consistent with the results of the present study.

However, other studies have found less microleakage with ZOE cement compared with resin-based or calcium hydroxide sealer cement. Shetty et al. evaluated the apical sealing of three root canal sealers, i.e. AH26®, Sealapex®, and Tubliseal® (Zinc Oxide Eugenol based), and observed a significant difference between Sealapex® and AH26® groups. Tubliseal® showed the least microleakage compared with the other two sealers.[4] A quantitative evaluation using four root canal sealers, i.e. Rocanal, AH Plus, Sealapex, and Root Canal (RC) Sealer, found a significant difference between Rocanal (ZOE), RC Sealer (polymeric resin based), and AH Plus. In this study, Sealapex had better sealing properties than AH Plus.[12]

Bouillaguet et al.[13] carried out a long-term comparison of the apical sealing capacity of different sealers in conjunction with the single-cone technique, reporting better results using GuttaFlow® and Epiphany® than with Pulp Canal Sealer® and AH Plus®; according to these authors, the leakage of AH-Plus® may be the result of inadequate bonding between the sealer and the gutta-percha point, allowing fluid to flow at the interface. Cement properties such as film thickness and subsequent dimensional changes during setting, solubility of its components, rheological properties, or the presence of smear layer could account for the lack of correlation between adhesion and leakage.[14],[15]

In addition, root sealing cement may be affected by the irrigating solutions used during endodontic therapy. The effect of chemical irrigants on dentin bonding is still unclear. In an in vitro study evaluating the microtensile regional bond strength of resin-based cement to root canal dentin reported a reduction in bond strength using 5% NaOCl solution for irrigation.[16] NaOCl may affect bond strength in the dentin layer because it impedes the formation of a consistent hybrid layer. In addition, protein chloramine-derived radical NaOCl-treated dentin results in incomplete polymerization of the adhesive resin. However, the deleterious effect of this irrigating solution may be reversed using antioxidant agents, such as ascorbic acid, sodium ascorbate, rosmarinic acid, and proanthocyanidin. These agents may improve the sealing ability of HA plus.[17]

This study identified that AH Plus, Sealapex, or Pulp Canal Sealer did not obtain complete obturation of the apex in all the teeth studied.[18] This finding agrees with other studies, despite the presence of newer sealing cement.[19]

Among the limitations of this study are those related to the method used to evaluate the microleakage that was performed ex vivo, and the conditions of the oral cavity cannot be replicated, especially the microbiological aspects of root canal treatment. However, clearing techniques and dye penetration methods have been used for many years, and their results are useful to evaluate apical microleakage.[20] The clearing technique was first used by Schultze in 1897 to visualize ossification centers in human embryos, and it is still in use in microleakage investigations.[4],[21] Clarification allows a three-dimensional evaluation of the teeth and visualization of the internal anatomy of the root canal, including lateral and accessory canals.[22] In this study, the frequency of dye penetration in the control group was 100% because the root canal was not filled, and this facilitated the verification of the effectiveness of the method used in the study. Moreover, clarification techniques offer the advantage of not having tissue loss as frequently occurs when the teeth are longitudinally or transversely sectioned.[20] However, clearing methods have some technical problems related to the use of demineralization and dehydration processes because some areas of the tooth may not be clearly observed. In addition, some of the dye may be dissolved during the clearing process.[23]

Both methylene blue and Indian ink have been used to study microleakages.[20] Methylene blue has good penetration within the canal because of its low molecular weight.[8] However, this substance may penetrate through the dentinal tubules, thus causing difficulties in precisely defining the level of apical penetration along the gutta-percha dentinal wall interface. Indian ink was used in this study because of its good penetration which is a result of its relatively small particular size (≤3 μm). It is, therefore, unlikely that this ink cannot infiltrate in areas where there is a periapical bacterial invasion.[20],[24] New methods to study microleakage may contribute to identification of the best sealing technique and products. Radioisotope penetration, electrochemical tests, bacterial and toxin infiltration, and animal experimental studies may provide more evidence on the performance of the different sealers used in root canal treatment.[23]

  Conclusion Top

Sealing ability appears to be greater for the resin-based sealer (AH Plus®) than for calcium hydroxide-based (Sealapex®) and the ZOE-based (Pulp Canal Sealer®) cement. However, the three root canal sealers used in the present study had some degree of dye penetration in some teeth. Therefore, careful disinfection of the canal and adequate filling of the root canals are essential for a successful endodontic treatment.

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Conflicts of interest

There are no conflicts of interest.

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